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Title: Expedition 389 Preliminary Report: Hawaiian Drowned Reefs
Our understanding of the mechanisms controlling eustatic sea level and global climate changes has been hampered by a lack of appropriate fossil coral records over the last 500 ky, particularly into and out of the glacial periods. This problem was addressed by International Ocean Discovery Program Expedition 389 by drilling a unique succession of Hawaiian drowned coral reefs now at 110–1300 meters below sea level (mbsl). The four objectives are to investigate (1) the timing, rate, and amplitude of sea level variability to examine cryosphere and geophysical processes, including the assessment of abrupt sea level change events; (2) the processes that determine changes in mean and high-frequency (seasonal–interannual) climate variability from times with different boundary conditions (e.g., ice sheet size, pCO2, and solar forcing); (3) the response of coral reef systems to abrupt sea level and climate changes; and (4) the variation through space and time of the subsidence and the volcanic evolution of the island. To achieve these objectives, 35 holes at 16 sites ranging 131.9–1241.8 mbsl were drilled during the expedition. A total of 425 m of core was recovered, comprising reef (83%) and volcanic (17%) material. Average core recoveries were 66%, with numerous intervals characterized by very well preserved mixtures of coralgal and microbialite frameworks with recoveries >90%. Some science-critical shallow sites were not drilled due to a failure to secure permits to operate in Hawaiian state waters. Furthermore, apart from one site the target penetration depths were not achieved. Preliminary radiometric dates indicate that the recovered reef deposits are from 488 to 13 ka in age. The Onshore Science Party took place in February 2024. Cores were CT and hyperspectral scanned and described. Standard measurements were made, and samples were taken for postcruise research. Preliminary assessment of the age and quality of the reef and basalt cores suggest that many of the expedition objectives will be met.  more » « less
Award ID(s):
1326927
PAR ID:
10505706
Author(s) / Creator(s):
; ;
Publisher / Repository:
International Ocean Discovery Program
Date Published:
Journal Name:
Preliminary report
Volume:
389
ISSN:
2372-9562
Subject(s) / Keyword(s):
International Ocean Discovery Program IODP MMA Valour Expedition 389 Hawaiian Drowned Reefs Earth’s Climate System Feedbacks in the Earth System Tipping Points in Earth’s History Site M0096 Site M0097 Site M0098 Site M0099 Site M0100 Site M0101 Site M0102 Site M0103 Site M0104 Site M0105 Site M0106 Site M0107 Site M0108 Site M0109 Site M0110
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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